Nanofibrous architecture presents unique biophysical cues to facilitate cellular responses and is considered an indispensable feature of a biomimetic three-dimensional (3D) scaffold and cell carrier. While electrospinning is a widely used method to prepare natural extracellular matrix-like nanofibers, it faces significant challenges to incorporate nanofibrous architecture into well-defined macroporous 3D scaffolds or injectable microspheres. Here we report a non-electrospinning approach that is generally effective at generating nanofibers from a variety of synthetic and natural biodegradable polymers and integrating these nanofibers into (1) 3D scaffolds with constructive geometry and designed internal macropore structures; and (2) injectable microspheres...

The response of blood vessels to physiological and pathological stimuli partly depends on the crosstalk between endothelial cells (EC) lining the luminal side and smooth muscle cells (SMC) building the inner part of the vascular wall. Thus, the in vitro analysis of the pathophysiology of blood vessels requires co-culture systems of EC and SMC. We have developed and validated a modified 3D sandwich co-culture (3D SW-CC) of EC and SMC employing open µ-Slides with a thin glass bottom allowing direct imaging. The culture dish comprises of an intermediate plate to minimize the meniscus resulting in homogenous cell distribution...

Tissue-engineered oral mucosal equivalents (OME) are being increasingly used to measure toxicity, drug delivery, and to model oral diseases. Current OME mainly comprise normal oral keratinocytes (NOK) cultured on top of a normal oral fibroblasts-containing matrix. However, the commercial supply of NOK is limited, restricting widespread use of these mucosal models. In addition, NOK suffer from poor longevity and donor-to-donor variability. Therefore, we constructed, characterized, and tested the functionality of OME based on commercial TERT2-immortalized oral keratinocytes (FNB6) to produce a more readily available alternative to NOK-based OME...

Monitoring of cell differentiation is a crucial aspect of cell-based therapeutic strategies depending on tissue maturation. In this study we have developed a non-invasive reporter system to trace murine skeletal muscle differentiation. Either a secreted bioluminescent reporter (Metridia luciferase) or a fluorescent reporter (GFP) was placed under the control of the truncated muscle creatine kinase (MCK) basal promoter enhanced by variable numbers of upstream MCK E-boxes. The engineered pE3MCK vector, coding a triple tandem of E-Boxes and the truncated MCK promoter, showed 20-fold higher levels of luciferase activation compared to a CMV promoter...

Decellularization of tissues and organs has high potential to obtain unique conformation and composition as native tissue structure but may result with weaken tissue mechanical strength. In this study poly(glycerol-sebacate) (PGS) elastomers were combined with decellularized aortae fragments to investigate the changes in mechanical properties. PGS prepolymer was synthesized via microwave irradiation then in-situ cross-linked within the decellularized aorta ECM. Tensile strength (σ) values were found comparable as 0...

Chondrogenic differentiation of human mesenchymal stem cells (MSCs) in 3D hydrogel holds promise as a method for repairing injured articular cartilage. Given MSC plasticity (its potential to mature into alternative lineages), non-destructive monitoring is critical for the optimization of chondrogenic differentiation conditions and the evaluation of the final product. However, conventional validation/assessment of the differentiation process (i.e. quantitative reverse transcription polymerase chain (qRT-PCR) and histology) are end-point assays requiring disruption of the sample...

The blood-brain barrier (BBB) maintains brain homeostasis but also presents a major obstacle to brain drug delivery. Brain microvascular endothelial cells (BMECs) form the principal barrier and therefore represent the major cellular component of in vitro BBB models. Such models are often used for mechanistic studies of the BBB in health and disease and for drug screening. Recently, human induced pluripotent stem cells (iPSCs) have emerged as a new source for generating BMEC-like cells for use in in vitro human BBB studies...

Natural extracellular matrix (ECM) derived biomaterials from decellularized allogenic tissues are of increasing interest for tissue engineering since their structure and composition provide a complexity that is not achievable with current manufacturing techniques. The prerequisite to bring allogenic tissue from bench to bedside as a functional biomaterial is the full removal of cells while preserving most of its native characteristics such as structure and composition. The exceptionally dense structure of articular cartilage, however, poses a special challenge for decellularisation, scaffold preparation and reseeding...

Traditional methods of cartilage tissue engineering rely on the use of scaffolds. Although successful chondrogenesis has been reported in scaffold-based constructs, the use of exogenous materials has limited their application due to eliciting host immunogenic responses, and potentially resulting in construct failure. As a result, tissue engineering approaches which aim to generate scaffold-free cartilaginous constructs have become of particular interest. Here, we generated scaffold-free cartilaginous constructs by cultivating expanded pediatric nasal chondrocyte multilayers in a Slow Turning Lateral Vessel (STLV) bioreactor system under chemically defined media...

Decellularized scaffolds composed of extracellular matrix (ECM) hold promise for repair and regeneration of the meniscus, given the potential for ECM-based biomaterials to aid in stem cell recruitment, infiltration, and differentiation. The objectives of this study were to decellularize canine menisci in order to fabricate a micronized, ECM-derived scaffold, and to determine the cytocompatibility and repair potential of the scaffold ex vivo. Menisci were decellularized with a combination of physical agitation and chemical treatments...

Numerous studies have shown the capabilities of 3D printing for use in the medical industry. At the time of this publication, basic home desktop 3-D printer kits can cost as little as $300, while medical-specific 3D bioprinters can cost upwards of $300,000. The purpose of this study was to show how a commercially available desktop 3D printer could be modified to bioprint an engineered poly-L-lactic acid (PLLA) scaffold containing viable chondrocytes in a bioink. Our bioprinter was used to create a living 3D functional tissue-engineered cartilage scaffold...

The development of an optimal animal model that could provide fast assessments of the interaction between bone and orthopedic implants is essential for both preclinical and theoretical researches in the design of novel biomaterials. Compared with other animal models, mice have superiority in accessing the well-developed transgenic modification techniques (e.g., cell tracing, knockoff, knockin, and so on), which serve as powerful tools in studying molecular mechanisms. In this study, we introduced the establishment of a mouse model, which was specifically tailored for the assessment of bone-implant interaction in a load-bearing bone marrow microenvironment and could potentially allow the molecular mechanism study of biomaterials by using transgenic technologies...

Elastin, critical for its structural and regulatory functions, is a missing link in vascular tissue engineering. Several elastin-inducting compounds have previously been reported, but their relative efficiency in promoting elastogenesis by adult arterial and venous vascular smooth muscle cells (VSMCs) and fibroblasts, four main vascular and elastogenic cells, has not been described. In addition to elasto-inductive substances, microRNA-29a was recently established as a potent post-transcriptional inhibitor of elastogenesis...

Engineered heart tissues made from human pluripotent stem cell-derived cardiomyocytes have been used for modeling cardiac pathologies, screening new therapeutics, and providing replacement cardiac tissue. Current methods measure the functional performance of engineered heart tissue by their twitch force and beating frequency, typically obtained by optical measurements. In this article, we describe a novel method for assessing twitch force and beating frequency of engineered heart tissue using magnetic field sensing, which enables multiple tissues to be measured simultaneously...

Cryopreservation of human umbilical vein endothelial cells (HUVECs) is important to tissue engineering applications and the study of the role of endothelial cells in cardiovascular and cerebrovascular diseases. The traditional methods for cryopreservation by vitrification (cooling samples to a cryogenic temperature without apparent freezing) using high concentration of cryoprotective agents (CPAs) and slow-freezing are suboptimal due to the severe toxicity of high concentration of CPAs and ice formation induced cryoinjuries, respectively...

Tissue-engineered heart valves are developed in bioreactors where biochemical and mechanical stimuli are provided for extracellular matrix formation. During this phase, the monitoring possibilities are limited by the need to maintain the sterility and the integrity of the valve. Therefore, noninvasive and nondestructive techniques are required. As such, optical imaging is commonly used to verify valve's functionality in vitro. It provides important information (i.e. leaflet symmetry, geometric orifice area, closing and opening times) which is, however, usually limited to a singular view along the central axis from the outflow side...

The cellular and molecular mechanisms that underpin regeneration of the human lung are unknown, and the study of lung repair has been impeded by the necessity for reductionist models that may exclude key components. We hypothesized that multicellular epithelial and mesenchymal cell clusters or lung organoid units (LuOU) could be transplanted to recapitulate proximal and distal cellular structures of the native lung and airways. Transplantation of LuOU resulted in the growth of tissue-engineered lung (TELu) that contained the necessary cell types consistent with native adult lung tissue and demonstrated proliferative cells at 2 and 4 weeks...

Transplantation of functional islets encapsulated in stable biomaterials has the potential to cure Type I diabetes. However, the success of these materials requires the ability to quantitatively evaluate their stability. Imaging techniques that enable monitoring of biomaterial performance are critical to further development in the field. X-ray phase-contrast (XPC) imaging is an emerging class of X-ray techniques that have shown significant promise for imaging biomaterial and soft tissue structures. In this study, XPC imaging techniques are shown to enable three dimensional (3D) imaging and evaluation of islet volume, alginate hydrogel structure, and local soft tissue features ex vivo...

Techniques to monitor the oxygen partial pressure (pO2) within implanted tissue-engineered grafts (TEGs) are critically necessary for TEG development, but current methods are invasive and inaccurate. In this study, we developed an accurate and noninvasive technique to monitor TEG pO2 utilizing proton ((1)H) or fluorine ((19)F) magnetic resonance spectroscopy (MRS) relaxometry. The value of the spin-lattice relaxation rate constant (R1) of some biocompatible compounds is sensitive to dissolved oxygen (and temperature), while insensitive to other external factors...